1. Field of the Invention
The present invention relates to a method for forming one or more graphene layers on a substrate. The method particularly relates to forming graphene from a treated portion of a diamond substrate.
2. Description of the Related Art
Recently, there has been much interest in a material known as graphene. Graphene is believed to be formed of a plane of carbon atoms that are sp2-bonded carbon to form a regular hexagonal lattice with an aromatic structure, such as a honeycomb crystal lattice. Graphene typically refers to a single planar sheet of covalently bonded carbon atoms and specifically refers to one sheet of graphite, i.e., the (0001) surface of graphite. Graphene can refer to one layer but can also refer to a number of layers less than ten layers. Graphite is made up of stacked layers of graphene bonded together by Van der Waals forces.
The interest in graphene is due, in part, to the potential uses of graphene in electronic devices. The ability to increase the speed and performance of electronic devices are at the heart of modern electronics. Graphene is a promising material for future electronics owing to its high carrier mobility, saturation velocity, electrical conductivity, thermal conductivity, and ability to integrate with almost any substrate. Attempts have been made to incorporate graphene into electronic devices, such as transistors, however such attempts have generally been unsuccessful due to problems associated with the production of high quality graphene layers of a size suitable for incorporation into such devices.
Graphene transistors are expected to enable the creation of computer chips that are hundreds of times faster than the current silicon-based parts. The main breakdown mechanism of graphene is mostly due to the Joule heating, which depends upon the thermal conductivity and surface roughness of the underlying substrate. Graphene on diamond substrates have attracted attention for their expected use in electronic devices as they are expected to have a higher conductivity on diamond substrate than silicon or carbide. The thermal conductivity of natural diamonds is around 22 W/(cm·K) and the thermal conductivity of synthetic diamonds is around 30 W/(cm·K), which makes diamond five to seven times better at conducting heat than copper. Graphene electrodes on diamond substrates are also expected to be more durable than metal electrodes on diamond substrates, the metal electrodes which are known to have poor adhesion with diamond due to inertness.
Thus, a method of fabrication of a graphene layer on a diamond substrate is desired.